We noticed the X-ray surface-brightness edge, where the surface-brightness drops (see Figures REF  and REF ) and therefore implies a discontinuity, or jump, in the gas density. The surface-brightnesses are \(S_{\rm x}\) (inside) and \(S_{\rm x}\) (outside) \(\approx \)  8.2 \(\pm \) 0.3 \(\times \)  10\(^{-6}\)  counts s\(^{-1}\)  arcsec\(^{-2}\)  and 3.7 \(\pm \) 0.3 \(\times \)  10\(^{-6}\)  counts s\(^{-1}\)  arcsec\(^{-2}\) , respectively. Consequently, our modeled densities in the two regions, \(\rho \) (inside) and \(\rho \) (outside) are approximately 2.9\(^{+0.2}_{-0.1}\)  \(\times \)  10\(^{-3}\)  cm\(^{-3}\)  and 1.9\(^{+0.2}_{-0.2}\)  \(\times \)  10\(^{-3}\)  cm\(^{-3}\) , respectively.
Our corresponding derived temperatures for the two regions, \(kT_{\rm (inside)}\)  and \(kT_{\rm (outside)}\)  are approximately 6.1\(^{+0.9}_{-0.8}\)  keV (\(\chi ^2\)  = 0.93 for 221 degrees of freedom) and 5.5\(^{+0.5}_{-0.4}\)  keV (\(\chi ^2\)  = 1.08 for 462 degrees of freedom), respectively.
We also repeated this exercise for a pie-circular aperture (shown in blue in Figure REF ) centered on the southern cD galaxy and lying toward the radio emission from the remnant radio galaxy with two regions containing the radio emission from the remnant radio galaxy and the smaller adjacent region toward the cD galaxy. The quantitative estimates from this are nearly identical and the fit statistics are at 90% confidence intervals. Although with large error bars, these density and temperature measurements are hinting that the surface-brightness edge toward the two cD galaxies is possibly a shock front.
Consequently, the observed density jump and the temperature jump across the edge, \(\rho _{\rm (inside)}\) /\(\rho _{\rm (outside)}\)  = 1.5\(^{+0.2}_{-0.2}\)  and \(kT_{\rm (inside)}\) /\(kT_{\rm (outside)}\)  = 1.1\(^{+0.7}_{-0.5}\)  suggest the Mach numbers, \(M\)  = 1.3\(^{+0.2}_{-0.2}\)  and 1.1\(^{+0.4}_{-0.3}\) , respectively under the Rankine-Hugoniot shock conditions for the intracluster gas, \(\gamma \)  = 5/3, which are all obviously in agreement, are within the error bars of [1]}.
We also believe that a smaller measure for the temperature jump is due to the contribution of cool thermal emission from the core to the adjacent region toward two cD galaxies, \(kT_{\rm (inside)}\) .
Note, it is equally possible that the surface-brightness edge is a cold front. Here, we assume it to be a shock front because of consistencies between our measurements and those of [1]} and [3]}.
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